http://en.wikipedia.org/wiki/Peer_pressure Peer pressure refers to the influence exerted by a peer group in encouraging a person to change his or her attitudes, values, or behavior in order to conform to group norms. Social groups affected include membership groups, when the individual is "formally" a member (for example, political party, trade union), or a social clique. A person affected by peer pressure may or may not want to belong to these groups. They may also recognize dissociative groups with which they would not wish to associate, and thus they behave adversely concerning that group's behaviors.